Brutus Innocentius

Greg Mankiw 21 Iulie 2011

I am a professor of economics at Harvard University, where I teach introductory economics (ec 10) among other courses.

A student emails me a question about the use of math in economics:

Dear Dr. Mankiw,

Hi, I am an undergraduate student studying economics in Michigan. I have recently become a big fan of your blog. I found your „Advice for Students” very helpful to professional economist-wannabes like me, and especially, those considering graduate study in economics. Your suggestion on math preparation for undergrads landed me on one simple question: „Do economists really use all that math?”

I was wondering if you could tell me how closely math and the works of professional economists at international organizations, such as World Bank and IMF, are related?

I look forward to your answer. Thank you in advance!

Best Regards,
[name withheld]

A student who wants to pursue a career in policy-related economics is advised to go to the best graduate school he or she can get into. The best graduate schools will expect to see a lot of math on your undergraduate transcript, so you need to take it. But will you use a lot of differential equations and real analysis once you land that dream job in a policy organization? No, you won’t.

That raises the question: Why do we academics want students that have taken a lot of math? There are several reasons:

1. Every economist needs to have a solid foundation in the basics of economic theory and econometrics, even if you are not going to be either a theorist or an econometrician. You cannot get this solid foundation without understanding the language of mathematics that these fields use.

2. Occasionally, you will need math in your job. In particular, even as a policy economist, you need to be able to read the academic literature to figure out what research ideas have policy relevance. That literature uses a lot of math, so you will need to be equipped with mathematical tools to read it intelligently.

3. Math is good training for the mind. It makes you a more rigorous thinker.

4. Your math courses are one long IQ test. We use math courses to figure out who is really smart.

5. Economics graduate programs are more oriented to training students for academic research than for policy jobs. Although many econ PhDs go on to policy work, all of us teaching in graduate programs are, by definition, academics. Some academics take a few years off to experience the policy world, as I did not long ago, but many academics have no idea what that world is like. When we enter the classroom, we teach what we know. (I am not claiming this is optimal, just reality.) So math plays a larger role in graduate classes than it does in many jobs that PhD economists hold.

Is it possible that admissions committees for econ PhD programs are excessively fond of mathematics on student transcripts? Perhaps. That is something I might argue with my colleagues about if I were ever put on the admissions committee. But a student cannot change that. The fact is, if you are thinking about a PhD program in economics, you are advised to take math courses until it hurts.

Since the time allocation is limited, I can take only some math courses and the problem is that I am not sure which courses are most important for a successful economist and which course I should take first. Can you possibly suggest for me a list of math courses that a typical economics student should take step by step?